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SubjectRe: [PATCH] eCryptFS: fix missed mutex_unlock
On Tue, May 20, 2008 at 11:28 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Sun, 18 May 2008 18:26:11 +0400 Cyrill Gorcunov <gorcunov@gmail.com> wrote:
>
>> ---
>>
>> Ingo, could you please apply it and test? Actually I really doubt if it help
>> with the locking problem you pointed. There are two procedures
>> in miscrev.c - ecryptfs_miscdev_poll() and ecryptfs_miscdev_read()
>> which takes/releases mutexes in a bit strange way... investigating,
>> but this patch is needed anyway.
>>
>> Index: linux-2.6.git/fs/ecryptfs/crypto.c
>> ===================================================================
>> --- linux-2.6.git.orig/fs/ecryptfs/crypto.c 2008-05-18 16:44:20.000000000 +0400
>> +++ linux-2.6.git/fs/ecryptfs/crypto.c 2008-05-18 17:56:12.000000000 +0400
>> @@ -1903,6 +1903,7 @@ int ecryptfs_get_tfm_and_mutex_for_ciphe
>> if (rc) {
>> printk(KERN_ERR "Error adding new key_tfm to list; "
>> "rc = [%d]\n", rc);
>> + mutex_unlock(&key_tfm_list_mutex);
>> goto out;
>> }
>> }
>
> Better to do it this way, I think:
>
> --- a/fs/ecryptfs/crypto.c~ecryptfs-fix-missed-mutex_unlock
> +++ a/fs/ecryptfs/crypto.c
> @@ -1906,9 +1906,9 @@ int ecryptfs_get_tfm_and_mutex_for_ciphe
> goto out;
> }
> }
> - mutex_unlock(&key_tfm_list_mutex);
> (*tfm) = key_tfm->key_tfm;
> (*tfm_mutex) = &key_tfm->key_tfm_mutex;
> out:
> + mutex_unlock(&key_tfm_list_mutex);
> return rc;
> }
> _
>
> Holding the lock for an additional few instructions may not be strictly
> needed, but we might avoid the reintroduction of such bugs?
>
>

Good idea, thanks! Could you update the patch, please?


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